The present invention pertains to a filter system in which a replaceable bag filter is enclosed in a tubular housing with a removable end cap and, more particularly, to such a system which is adaptable to accommodate a wide range of bag filter constructions without any changes in the construction of the housing and end cap.
Replaceable bag filters and systems utilizing them are well known in the art. Such filter systems are applied to filter a wide variety of liquids including inks, paints, and alcoholic beverages including beer and wine. Typically, such a filter system includes an open ended tubular housing and an enclosing end cap. A replaceable filter bag is placed within the housing and the peripheral edge of its open upper end is sealed as the cap is replaced on the housing. The cloth-like filter bag is typically supported in the housing within an open mesh tubular basket or cage which is also typically suspended within the housing.
One well known filter bag construction is shown in various embodiments in U.S. Pat. Nos. 4,285,814; 4,669,167; and 5,137,632. This filter bag includes conventional flexible cloth-like filter media attached to an impervious plastic collar which defines the open end of the bag. The peripheral edge of the collar is defined by an annular lip having the shape of an inverted V and various constructions of housings and end caps are specifically designed to mount and seal filter bags having this construction. However, these housings and end caps cannot be used with any other type of filter bag.
Filter bags are also available which do not have the unique collar and V-shaped lip characteristic of the constructions shown in the foregoing patents. Such bag filters may have a flexible annular end sleeve defining the opening of the bag which may be a flexible cloth of somewhat heavier or lighter construction than the bag filter media itself, or simply an extension of the filter bag.
All of the foregoing types of bag filters are available in the replacement market, but the user is typically restricted to a single type for which the housing and end cap, and possibly the retaining cage, were specifically constructed. Another problem common to all bag filters is that their fairly light weight construction and high flexibility often make them difficult to insert into the retaining cage or basket without wrinkling and collapsing.
It would, therefore, be most desirable to have a bag filter system in which the housing, end cap and bag-retaining cage could be utilized with different types of commonly available replaceable filter bags. Further, an improved filter bag construction which facilitates replacement would also be desirable.